Water-dispersible polymers, a method of making same and items using same

ABSTRACT

The present invention is directed to water-dispersible polymers. The present invention is also directed to a method of making water-dispersible polymers and their applicability as binder compositions. The present invention is further directed to fiber-containing fabrics and webs comprising water-dispersible binder compositions and their applicability in water-dispersible personal care products.

FIELD OF THE INVENTION

The present invention is directed to water-dispersible polymerformulations. The present invention is also directed to a method ofmaking water-dispersible polymer formulations and their applicability asbinder compositions for disposable items. The present invention isfurther directed to disposable items, such as wet-wipes, comprisingwater-dispersible binder compositions.

BACKGROUND OF THE INVENTION

For many years, the problem of disposability has plagued industries thatprovide disposable items, such as, diapers, wet wipes, incontinentgarments and feminine care products. While much headway has been made inaddressing this problem, one of the weak links has been the inability tocreate an economical coherent fibrous web, which will readily dissolveor disintegrate in water, but still have sufficient in-use strength.See, for example, U.K. patent disclosure 2,241,373 and U.S. Pat. No.4,186,233. Without such a product, the ability of the user to dispose ofthe product by flushing it down the toilet is greatly reduced, if noteliminated. Furthermore, the ability of the product to disintegrate in alandfill is quite limited because a large portion of the productcomponents, which may well be biodegradable or photodegradable, areencapsulated in or bound together by plastic which degrades over a longperiod of time, if at all. Accordingly, if the plastic disintegrated inthe presence of water, the internal components could degrade as a resultof the rupture of the plastic encapsulation or binding.

Disposable products, such as diapers, feminine care products and adultincontinent care products may be made to be disposed by flushing downtoilets. Usually such products comprise a body side liner which mustrapidly pass fluids, such as urine or menses, so that the fluid may beabsorbed by an absorbent core of the product. Typically, the body sideliner may be a coherent fibrous web, which desirably possesses a numberof characteristics, such as softness and flexibility. The fibrous web ofthe body side liner material may be typically formed by wet or dry (air)laying a generally random plurality of fibers and joining them togetherto form a coherent web with a binder compositions. Past bindercompositions have performed this function well. However, fibrous webscomprising these compositions tended to be non-dispersible and presentproblems in typical household sanitation systems.

Recent binder compositions have been developed which can be moredispersible and are more environmentally responsible than past bindercompositions. One class of binder compositions includes polymericmaterials having inverse solubility in water. These binder compositionsare insoluble in warm water, but are soluble in cold water, such asfound in a toilet. It is well known that a number of polymers exhibitcloud points or inverse solubility properties in aqueous media. Thesepolymers have been cited in several publications for variousapplications, including (1) as evaporation retarders (JP 6207162); (2)as temperature sensitive compositions, which are useful as temperatureindicators due to a sharp color change associated with a correspondingtemperature change (JP 6192527); (3) as heat sensitive materials thatare opaque at a specific temperature and become transparent when cooledto below the specific temperature (JP 51003248 and JP 81035703); (4) aswound dressings with good absorbing characteristics and easy removal (JP6233809); and (5) as materials in flushable personal care products (U.S.Pat. No. 5,509,913, issued to Richard S. Yeo on Apr. 23, 1996 andassigned to Kimberly-Clark Corporation).

Other recent binders of interest include a class of binders, which areion-sensitive. Several U.S. and European patents assigned to LionCorporation of Tokyo, Japan, disclose ion-sensitive polymers comprisingacrylic acid and alkyl or aryl acrylates. See U.S. Pat. Nos. 5,312,883,5,317,063 and 5,384,189, the disclosures of which are incorporatedherein by reference, as well as, European Pat. No. 608460A1. In U.S.Pat. No. 5,312,883, terpolymers are disclosed as suitable binders forflushable nonwoven webs. The disclosed acrylic acid-based terpolymers,which comprise partially neutralized acrylic acid, butyl acrylate and2-ethylhexyl acrylate, are suitable binders for use in flushablenonwoven webs in some parts of the world. However, because of thepresence of a small amount of sodium acrylate in the partiallyneutralized terpolymer, these binders fail to disperse in watercontaining more than about 15 ppm Ca² ⁺ and/or Mg²⁺. When placed inwater containing more than about 15 ppm Ca² ⁺ and/or Mg² ⁺ ions,nonwoven webs using the above-described binders maintain a tensilestrength greater than 30 g/in, which negatively affects the“dispersibility” of the web. The proposed mechanism for the failure isthat each calcium ion binds with two carboxylate groups eitherintramolecularly or intermolecularly. Intramolecular association causesthe polymer chain to coil up, which eventually leads to polymerprecipitation. Intermolecular association yields crosslinking. Whetherintramolecular or intermolecular associations are taking place, theterpolymer is not soluble in water containing more than about 15 ppm Ca²⁺ and/or Mg² ⁺. Due to the strong interaction between calcium ions andthe carboxylate groups of the terpolymer, dissociation of the complex ishighly unlikely because this association is irreversible. Therefore, theabove described polymer that has been exposed to a high Ca² ⁺ and/or Mg²⁺ concentration solution will not disperse in water even if the calciumconcentration decreases. This limits the application of the polymer as aflushable binder material because most areas across the U.S. have hardwater, which contains more than 15 ppm Ca² ⁺ and/or Mg² ⁺.

In a co-pending application assigned to Kimberly Clark; i.e., U.S.patent application Ser. No. 09/223,999, filed Dec. 31, 1998, thedisclosure of which is incorporated herein by reference, there isdisclosed a modification of the acrylic acid terpolymers of theabove-referenced patents to Lion Corporation. Specifically, U.S. patentapplication Ser. No. 09/223,999 discloses a sulfonate anion modifiedacrylic acid terpolymers which has improved dispersibility in relativelyhard water; e.g., up to 200 ppm Ca² ⁺ and/or Mg² ⁺, compared to theunmodified Lion polymers. However, the Lion Corporation ion-sensitivepolymers of the above-referenced patents and the sulfonate anionmodified acrylic acid terpolymers of the co-pending application, whenused as binders for personal care products, such as wet wipes, typicallyhave reduced sheet wettability, increased sheet stiffness, increasedsheet stickiness, reduced binder sprayability and relatively highproduct cost.

Another approach to dispersible personal care products is disclosed inU.S. Pat. No. 5,281,306 to Kao Corporation of Tokyo, Japan (thedisclosure of which is incorporated herein by reference). This patentdiscloses a water-disintegratable cleansing sheet; i.e., wet wipe,comprising water-dispersible fibers treated with a water-soluble polymerbinder having a carboxyl group. Examples of water-soluble binders havinga carboxyl group include, carboxymethyl cellulose, methacrylicacid-lauryl methacrylate, polyacrylic acid, polymethacrylic acidcopolymers of ethyl hexyl acetate, butyl acrylate and acrylic acid, andsalts thereof. The cleansing sheet is treated with a cleansing agentcontaining 5%-95% of a water-compatible organic solvent and 95%-5%water. A preferred organic solvent is propylene glycol. The cleansingsheet does not disperse in the organic solvent-based cleansing agent,but disperses in water. The cleansing sheet also includes a metallic ionselected from alkaline earth metals, such as magnesium, calcium,strontium, barium, manganese, zinc, cobalt and nickel. Although the Kaopatent indicates that all polymers containing carboxyl groups maintainwet strength, not all polymers so disclosed, such as polyacrylic acidand salts thereof, satisfactorily maintain wet strength.

Although many patents disclose various ion and temperature sensitivecompositions for water-dispersible or flushable materials, there existsa need for dispersible products possessing softness, flexibility, threedimensionality, and resiliency; wicking and structural integrity in thepresence of body fluids (including feces) at body temperature; and truefiber dispersion after toilet flushing so that fibers do not becomeentangled with tree roots or at bends in sewer pipes. In addition, theknown ion-sensitive polymers, such as those of Lion Corporation and theco-pending application of Kimberly Clark, have relatively highviscosities at high shear rates that make application by sprayingimpossible or impractical. Moreover, there is a need in the art forflushable products having water-dispersibility in all areas of theworld, including soft and hard water areas. Furthermore, there is a needfor water-dispersible binders that do not reduce wettability of productwith which they are used and are sprayable for easy and uniformapplication to and penetration into products.

SUMMARY OF THE INVENTION

The present invention is directed to polymer formulations, which havebeen developed to address the above-described problems associated withcurrently available, water-dispersible polymers and other polymersdescribed in literature. The polymer formulations of the presentinvention are insoluble in a wetting composition comprising 5%-95% of awater-compatible organic solvent and 95%-5% water, but is soluble inwater, including water containing divalent salt solutions, such as hardwater with up to 200 ppm (parts per million) calcium and magnesium ions.Unlike some water-dispersible polymer binder formulations which lose wetstrength, the polymer formulations of the present invention retainsignificant wet strength. Consequently, flushable products containingthe polymer formulations of the present invention maintain strength whenwetted with a wetting solution, but are dispersibility in hard water.Furthermore, the polymer formulations of the present invention haveimproved properties of sprayability.

The polymer formulations of the present invention are useful as bindersand structural components for air-laid and wet-laid nonwoven fabrics forapplications such as body-side liners, fluid distribution materials,fluid in-take materials (surge) or cover stock in various personal careproducts. The polymer formulations of the present invention areparticularly useful as a binder material for flushable personal careproducts, particularly wet wipes for personal use such as cleaning ortreating skin, makeup removal, nail polish removal, medical care, andalso wipes for use in hard surface deaning, automotive care, includingwipes comprising cleaning agents, disinfectants, and the like. Theflushable products maintain integrity or wet strength during storage anduse, and break apart or disperse after disposal in the toilet when theorganic solvent concentration falls below a critical level. Suitablesubstrates for treatment include tissue, such as creped or uncrepedtissue, coform products, hydroentangled webs, airlaid mats, fluff pulp,nonwoven webs, and composites thereof. Methods for producing uncrepedtissues and molded three-dimensional tissue webs of use in the presentinvention can be found in commonly owned U.S. patent application, Ser.No. 08/912,906, “Wet Resilient Webs and Disposable Articles MadeTherewith,” by F. -J. Chen et al., filed Aug. 15, 1997; U.S. Pat. No.5,429,686, issued to Chiu et al. on Jul. 4, 1995; U.S. Pat. No.5,399,412, issued to S. J. Sudall and S. A. Engel on Mar. 21, 1995; U.S.Pat. No. 5,672,248, issued to Wendtet al. on Sept. 30, 1997; and U.S.Pat. No. 5,607,551, issued to Farrington et al. on Mar. 4, 1997; all ofwhich are herein incorporated in their entirety by reference. The moldedtissue structures of the above patents can be especially helpful inproviding good cleaning in a wet wipe. Good cleaning can also bepromoted by providing a degree of texture in other substrates as well byembossing, molding, wetting and through-air drying on a textured fabric,and the like.

Airlaid material can be formed by metering an airflow containing thefibers and other optional materials, in substantially dry condition,onto a typically horizontally moving wire forming screen. Suitablesystems and apparatus for air-laying mixtures of fibers andthermoplastic material are disclosed in, for example, U.S. Pat. No.4,157,724 (Persson), issued Jun. 12, 1979, and reissued Dec. 25, 1984 asRe. U.S. Pat. No. 31,775; U.S. Pat. No. 4,278,113 (Persson), issued Jul.14, 1981; U.S. Pat. No. 4,264,289 (Day), issued Apr. 28, 1981; U.S. Pat.No. 4,352,649 (Jacobsen et al.), issued Oct. 5, 1982; U.S. Pat. No.4,353,687 (Hosler, et al.), issued Oct. 12, 1982; U.S. Pat. No.4,494,278 (Kroyer, et al.), issued Jan. 22, 1985; U.S. Pat. No.4,627,806 (Johnson), issued Dec. 9, 1986; U.S. Pat. No. 4,650,409(Nistri, et al.), issued Mar. 17, 1987; and U.S. Pat. No. 4,724,980(Farley), issued Feb. 16, 1988; and U.S. Pat. No. 4,640,810 (Laursen etal.), issued Feb. 3, 1987.

The present invention also discloses how to make water-dispersiblenonwovens, including cover stock (liner), intake (surge) materials andwet wipes, which are stable in fluids having 5%-95% of awater-compatible organic solvent and 95%-5% water, using theabove-described unique polymer formulations as binder compositions. Theresultant nonwovens are flushable and water-dispersible due to the waterdispersibility of the binder. The polymer formulations with which sucharticles are treated can have improved properties of sprayability, whichimproves polymer distribution on the product and penetration into theproduct, in addition to ease of application, which translates into costsavings.

These and other objects, features and advantages of the presentinvention will become apparent after a review of the following detaileddescription of the disclosed embodiments and the appended drawing andclaims.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

In order to be an effective polymer formulation suitable for use influshable or water-dispersible personal care products, the formulationsshould desirably be (1) functional; i.e., maintain wet strength undercontrolled conditions and dissolve or disperse rapidly in soft or hardwater such as found in toilets and sinks around the world; (2) safe (nottoxic); and (3) relatively economical. In addition to the foregoingfactors, the polymer formulations when used as a binder composition fora non-woven substrate, such as a wet wipe, desirably should be (4)processable on a commercial basis; i.e., may be applied relativelyquickly on a large scale basis, such as by spraying, which therebyrequires that the binder composition have a relatively low viscosity athigh shear; and (5) provide acceptable levels of sheet or substratewettability. The wetting composition with which the wet wipes of thepresent invention are treated can provide some of the foregoingadvantages, and, in addition, can provide (6) improved skin care, suchas reduced skin irritation or other benefits. The polymer formulationsof the present invention and articles made therewith, especially wetwipes comprising particular wetting compositions set forth below, canmeet many or all of the above criteria. Of course, it is not necessaryfor all of the advantages of the preferred embodiments of the presentinvention to be met to fall within the scope of the present invention.

The polymer formulations of the present invention are formed from ablend of two polymers. One of the polymers of the polymer formulationsof the present invention is a synthetic water-soluble polymer.Water-soluble polymers useful in the present invention includewater-soluble polymer containing carboxylate groups which also haveflexible polymer chains. Such water-soluble polymers are disclosed inU.S. Pat. No. 5,281,306, the disclosure of which is incorporated hereinby reference in its entirety. A useful water-soluble polymer is sodiumpolyacrylate. A sodium polyacrylate useful in the present invention iscommercially available under the designation NS 9893-92A and NS 9893-92Bfrom National Starch and Chemical Co., Bridgewater, N.J.

Water-soluble acrylic acid copolymers useful in the present inventionmay comprise any combination of acrylic acid monomers and acrylic ester(alkyl acrylate) monomers capable of free radical polymerization into acopolymer. Suitable acrylic acid monomers include, but are not limitedto, acrylic acid and methacrylic acid. Suitable acrylic monomersinclude, but are not limited to, acrylic esters and methacrylic estershaving an alkyl group of 1 to 18 carbon atoms or a cycloalkyl group of 3to 18 carbonatoms and it is preferred that acrylic esters and/ormethacrylic esters having an alkyl group of 1 to 12 carbon atoms or acycloalkyl group of 3 to 12 carbon atoms may be used singly or incombination.

The relative amounts of the monomers in the acrylic acid copolymer ofthe present invention may vary depending on the desired properties inthe resulting polymer. The mole percent of acrylic acid monomer in thecopolymer is up to about 70 mole percent. More specifically, the molepercent of acrylic acid monomer in the copolymer is from about 15 toabout 50 mole percent. Most specifically, the mole percent of acrylicacid monomer in the copolymer is from about 25 to about 40 mole percent.

More specifically, examples of the acrylic acid copolymers useful in thepresent invention include copolymers of 10 weight percent to 90 weightpercent, desirably 20 weight percent to 70 weight percent of acrylicacid and/or methacrylic acid and 90 weight percent to 10 weight percent,desirably 80 weight percent to 30 weight percent of acrylic estersand/or methacrylic esters having an alkyl group of 1 to 18 carbon atomsor a cycloalkyl group of 3 to 18 carbon atoms in which 1 to 60 molepercent, desirably 5 to 50 mole percent of acrylic acid and/ormethacrylic acid is neutralized to form a salt; or copolymers of 30weight percent to 75 weight percent, desirably 40 weight percent to 65weight percent of acrylic acid, 5 weight percent to 30 weight percent,desirably 10 weight percent to 25 weight percent of acrylic estersand/or methacrylic esters having an alkyl group of 8 to 12 carbon atomsand 20 weight percent to 40 weight percent; desirably 25 weight percentto 35 weight percent of acrylic esters and/or methacrylic esters havingan alkyl group of 2 to 4 carbon atoms in which 1 to 50 mole percent,desirably 2 to 40 mole percent of acrylic acid is neutralized to form asalt.

The acrylic acid copolymers of the present invention may have an averagemolecular weight, which varies depending on the ultimate use of thepolymer. The acrylic acid copolymers of the present invention have aweight average molecular weight ranging from about 10,000 to about5,000,000. More specifically, the acrylic acid copolymers of the presentinvention have a weight average molecular weight ranging from about25,000 to about 2,000,000, or, more specifically still, from about200,000 to about 1,000,000.

The acrylic acid copolymers of the present invention may be preparedaccording to a variety of polymerization methods, desirably a solutionpolymerization method. Suitable solvents for the polymerization methodinclude, but are not limited to, lower alcohols such as methanol,ethanol and propanol; a mixed solvent of water and one or more loweralcohols mentioned above; and a mixed solvent of water and one or morelower ketones such as acetone or methyl ethyl ketone.

In the polymerization methods of the present invention, anypolymerization initiator may be used. Selection of a particularinitiator may depend on a number of factors including, but not limitedto, the polymerization temperature, the solvent, and the monomers used.Suitable polymerization initiators for use in the present inventioninclude, but are not limited to, 2,2′-azobisisobutyronitrile,2,2′-azobis(2-methylbutyronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(2-amidinopropane)dihydrochloride,2,2′-azobis(N,N′-dimethyleneisobutylamidine), potassium persulfate,ammonium persulfate, and aqueous hydrogen peroxide. The amount ofpolymerization initiator may desirably range from about 0.01 to 5 weightpercent based on the total weight of monomer present.

The polymerization temperature may vary depending on the polymerizationsolvent, monomers, and initiator used, but in general, ranges from about20° C. to about 90° C. Polymerization time generally ranges from about 2to about 8 hours.

If polyacrylic acid is used as one of the monomers, it is desired toneutralize at least a portion of the acid component. Any inorganic baseor organic base may be used as a neutralizing agent to neutralize theacid component. Examples of neutralizing agents include, but are notlimited to, inorganic bases, such as sodium hydroxide, potassiumhydroxide, lithium hydroxide and sodium carbonate, and amines, such asmonoethanolamine, diethanolamine, diethylaminoethanol, ammonia,trimethylamine, triethylamine, tripropylamine, morpholine. Preferredneutralizing agents include sodium hydroxide, potassium hydroxide, or acombination thereof.

In a further embodiment of the present invention, the above-describedwater-soluble polymer formulations are used as binder materials forflushable and/or non-flushable products. In order to be effective as abinder material in flushable products throughout the United States, theion-sensitive polymer formulations of the present invention remainstable and maintain their integrity while dry or in a wettingcomposition comprising 5%-95% of a water-compatible organic solvent and95%-5% water, but is soluble in water, including water containingdivalent salt solutions, such as hard water with up to 200 ppm (partsper million) calcium and magnesium ions. Desirably, the ion-sensitivepolymer formulations of the present invention including acrylic acidcopolymers are insoluble in a composition comprising 20%water-compatible organic solvent and 80% water.

As stated above, the polymer formulations of the present invention areformed from a combination of two or more different polymers, wherein atleast one polymer is water-soluble polymer. The second polymer is anemulsion polymer. Furthermore, the emulsion polymer may be insoluble inwater and can reduce the shear viscosity of the water-soluble polymer.Examples of emulsion polymers useful in the present invention include,but are not limited to, styrene acrylic emulsions and styrenebutadieneemulsions. Styrene emulsions useful in the present invention arecommercially available under the designation Rhoplex P-308 and RhoplexNW-1715K from Rohm and Haas, Philadelphia, Pa. Styrene-butadieneemulsions useful in the present invention are commercially availableunder the designation Rovene 4470, Rovene 4457 and Rovene 4817 fromMallard Creek Polymers, Charlotte, N.C.

In the polymer blend of the present invention, the water-soluble polymeris present in an amount of approximately 50% to 95% by weight and theemulsion polymer is present in an amount of approximately 5% to 50% byweight. Desirable, the water-soluble polymer is present in an amount ofapproximately 70% to 90% by weight and the emulsion polymer is presentin an amount of approximately 10% to 30% by weight.

In blending the water-soluble polymer and the emulsion polymer, thesequence of blending is important. One must avoid procedures that couldshock the surfactant systems of the emulsion polymers. The procedurefollowed in the present invention is to initially dilute thewater-soluble polymer with water. Then, while stirring the dilutedwater-soluble polymer, the emulsion polymer is slowly added to thewater-soluble polymer.

Desirably, but not necessarily, the emulsion polymer when combined withthe water-soluble polymer will reduce the shear viscosity of thewater-soluble polymer to such an extent that the combination of thewater-soluble polymer and the emulsion polymer is sprayable. Bysprayable is meant that the polymer can be applied to a nonwoven fibroussubstrate by spraying and the distribution of the polymer across thesubstrate and the penetration of the polymer into the substrate are suchthat the polymer formulation is uniformly applied to the substrate.

The co-binder polymer can be in the form of an emulsion latex. Thesurfactant system used in such a latex emulsion should be such that itdoes not substantially interfere with the dispersibility of thewater-soluble polymer.

The emulsion polymer of the present invention can have an averagemolecular weight, which varies depending on the ultimate use of thepolymer. Desirably, the emulsion polymer has a weight average molecularweight ranging from about 500,000 to about 200,000,000. More desirably,the emulsion polymer has a weight average molecular weight ranging fromabout 500,000 to about 100,000,000.

Emulsion polymers that can meet many or all of the foregoing criteriainclude, but are not limited to, poly(ethylene-vinyl acetate),poly(styrene-butadiene), poly(styrene-acrylic), a vinyl acrylicterpolymer, neoprene, a polyester latex, an acrylic emulsion latex, polyvinyl chloride, ethylene-vinyl chloride copolymer, a carboxylated vinylacetate latex, and the like. A particularly preferredpoly(styrene-butadiene) is Rovene® 4817 available from Mallard CreekPolymers, Charlotte, N.C. A particularly preferred poly(styrene-acrylic)is Rhoplex® NM 1715K available from Rohm and Haas, Philadelphia, Pa.

As stated above, useful emulsion polymers can include a variety ofcommercial latex emulsions, including those selected from the Rovene®series (styrene butadiene latices available from Mallard Creek Polymersof Charlotte, N.C.), the Rhoplex® latices of Rohm and Haas Company, andthe Elite® latices of National Starch. Polymer emulsions or dispersionsgenerally comprise small polymer particles, such as crosslinkableethylene vinyl acetate copolymers, typically in spherical form,dispersed in water and stabilized with surface active ingredients, suchas low molecular weight emulsifiers or high molecular weight protectivecolloids. These liquid binders can be applied to airlaid webs or othersubstrates by methods known in the art of binder treatment for nonwovenwebs, including spray or foam application, flooded nip impregnation,curtain coating, etc., followed by drying. In general, a wide variety oflatex compounds and other resins or emulsions can be considered,including vinyl acetate copolymer latices, such as 76 RES 7800 fromUnion Oil Chemicals Divisions and Resyn® 25-1103, Resyn® 25-1109, Resyn®25-1119, and Resyn® 25-1189 from National Starch and ChemicalCorporation, ethylene-vinyl acetate copolymer emulsions, such asAirflex® ethylene-vinylacetate from Air Products and Chemicals Inc.,acrylic-vinyl acetate copolymer emulsions, such as Rhoplex® AR-74 fromRohm and Haas Company, Synthemul® 97-726 from Reichhold Chemicals Inc.,Resyn® 25-1140, 25-1141, 25-1142, and Resyn-6820 from National Starchand Chemical Corporation, vinyl acrylic terpolymer latices, such as 76RES 3103 from Union Oil Chemical Division, and Resyn® 251110 fromNational Starch and Chemical Corporation, acrylic emulsion latices, suchas Rhoplex® B-15J, Rhoplex® P-376, Rhoplex® TR-407, Rhoplex® E-940,Rhoplex® TR934, Rhoplex® TR-520, Rhoplex® HA-24, and Rhoplex® NW1825from Rohm and Haas Company, and Hycar® 2600×322, Hycar® 2671, Hycar®2679, Hycar® 26120, and Hycar® 2600×347 from B. F. Goodrich ChemicalGroup, styrene-butadiene latices, such as 76 RES 4100 and 76 RES 8100available from Union Oil Chemicals Division, Tylac® resin emulsion68-412, Tylac® resin emulsion 68-067, 68-319, 68-413, 68-500, 68-501,available from Reichhold Chemical Inc., and DL6672A, DL6663A, DL6638A,DL6626A, DL6620A, DL615A, DL617A, DL620A, DL640A, DL650A available fromDow Chemical Company; and rubber latices, such as neoprene availablefrom Serva Biochemicals; polyester latices, such as Eastman AQ 29Davailable from Eastman Chemical Company; vinyl chloride latices, such asGeon® 352 from B. F. Goodrich Chemical Group; ethylene-vinyl chloridecopolymer emulsions, such as Airflex® ethylene-vinyl chloride from AirProducts and Chemicals; polyvinyl acetate homopolymer emulsions, such asVinac® from Air Products and Chemicals; carboxylated vinyl acetateemulsion resins, such as Synthemul® synthetic resin emulsions 40-502,40-503, and 97-664 from Reichhold Chemicals Inc. and Polyco® 2149, 2150,and 2171 from Rohm and Haas Company. Silicone emulsions can also beconsidered.

Polymer Formulations and Fabrics Containing the Same

The polymer formulations of the present invention may be used asbinders. The binder formulations of the present invention may be appliedto any fibrous substrate. The binders are particularly suitable for usein water-dispersible products. Suitable fibrous substrates include, butare not limited to, nonwoven and woven fabrics. In many embodiments,particularly personal care products, preferred substrates are nonwovenfabrics. As used herein, the term “nonwoven fabric” refers to a fabricthat has a structure of individual fibers or filaments randomly arrangedin a mat-like fashion (including papers). Nonwoven fabrics can be madefrom a variety of processes including, but not limited to, air-laidprocesses, wet-laid processes, hydroentangling processes, staple fibercarding and bonding, and solution spinning.

The binder composition may be applied to the fibrous substrate by anyknown process of application. Suitable processes for applying the bindermaterial include, but are not limited to, printing, spraying,electrostatic spraying, coating, flooded nips, metered press rolls,impregnating or by any other technique. The amount of binder compositionmay be metered and distributed uniformly within the fibrous substrate ormay be non-uniformly distributed within the fibrous substrate. Thebinder composition may be distributed throughout the entire fibroussubstrate or it may be distributed within a multiplicity of smallclosely spaced areas. In most embodiments, uniform distribution ofbinder composition is desired.

For ease of application to the fibrous substrate, the binder may bedissolved in water, or in a non-aqueous solvent, such as methanol,ethanol, acetone, or the like, with water being the preferred solvent.The amount of binder dissolved in the solvent may vary depending on thepolymer used and the fabric application. Desirably, the binder solutioncontains up to about 25 percent by weight of binder composition solids.More desirably, the binder solution contains from about 10 to 20 percentby weight of binder composition solids, especially about 12 percent byweight binder composition solids. Plasticizers, perfumes, coloringagents, antifoams, bactericides, preservative, surface active agents,thickening agents, fillers, opacifiers, tackifiers, detackifiers, andsimilar additives can be incorporated into the solution of bindercomponents, if so desired.

Once the binder composition is applied to the substrate, the substrateis dried by any conventional means. Once dry, the coherent fibroussubstrate exhibits improved tensile strength when compared to thetensile strength of the untreated wet-laid or dry-laid substrates, andyet has the ability to rapidly “fall apart”, or disintegrate when placedin soft or hard water having a relatively high multivalent ionicconcentration and agitated. For example, the dry tensile strength of thefibrous substrate may be increased by at least 25 percent as compared tothe dry tensile strength of the untreated substrate not containing thebinder. More particularly, the dry tensile strength of the fibroussubstrate may be increase by at least 100 percent as compared to the drytensile strength of the untreated substrate not containing the binder.Even more particularly, the dry tensile strength of the fibroussubstrate may be increased by at least 500 percent as compared to thedry tensile strength of the untreated substrate not containing thebinder.

A desirable feature of the present invention is that the improvement intensile strength is effected where the amount of binder compositionpresent, “add-on”, in the resultant fibrous substrate represents only asmall portion by weight of the entire substrate. The amount of “add-on”can vary for a particular application; however, the optimum amount of“add-on” results in a fibrous substrate which has integrity while in useand also quickly disperses when agitated in water. For example, thebinder components typically are from about 5 to about 65 percent, byweight, of the total weight of the substrate. More particularly, thebinder components may be from about 10 to about 35 percent, by weight,of the total weight of the substrate. Even more particularly, the bindercomponents may be from about 17 to about 22 percent by weight of thetotal weight of the substrate.

The nonwoven fabrics of the present invention have good in-use tensilestrength. Desirably, the nonwoven fabrics of the present invention areabrasion resistant and retain significant tensile strength in aqueoussolutions containing greater than about 0.5 weight percentwater-compatible organic solvent. Yet, the nonwoven fabrics aredispersible in very soft to moderately hard to hard water. Because ofthis latter property, nonwoven fabrics of the present invention are wellsuited for disposable products, such as pre-moistened wipes (wet wipes),which can be thrown in a flush toilet after use in any part of theworld.

The fibers forming the fabrics above can be made from a variety ofmaterials including natural fibers, synthetic fibers, and combinationsthereof. The choice of fibers depends upon, for example, the intendedend use of the finished fabric and fiber cost. For instance, suitablefibrous substrates may include, but are not limited to, natural fiberssuch as cotton, linen, jute, hemp, wool, wood pulp, etc. Similarly,regenerated cellulosic fibers, such as viscose rayon and cuprammoniumrayon, modified cellulosic fibers, such as cellulose acetate, orsynthetic fibers, such as those derived from polypropylenes,polyethylenes, polyolefins, polyesters, polyamides, polyacrylics, etc.,alone or in combination with one another, may likewise be used. Blendsof one or more of the above fibers may also beused, if so desired. Amongwood pulp fibers, any known papermaking fibers may be used, includingsoftwood and hardwood fibers. Fibers, for example, may be chemicallypulped or mechanically pulped, bleached or unbleached, virgin orrecycled, high yield or low yield, and the like. Mercerized, chemicallystiffened or crosslinked fibers may also be used.

Synthetic cellulose fiber types include rayon in all its varieties andother fibers derived from viscose or chemically modified cellulose,including regenerated cellulose and solvent-spun cellulose, such asLyocell. Chemically treated natural cellulosic fibers can be used, suchas mercerized pulps, chemically stiffened or crosslinked fibers, orsulfonated fibers. Recycled fibers, as well as virgin fibers, can beused. Cellulose produced by microbes and other cellulosic derivativescan be used. As used herein, the term “cellulosic” is meant to includeany material having cellulose as a major constituent, and, specifically,comprising at least 50 percent by weight cellulose or a cellulosederivative. Thus, the term includes cotton, typical wood pulps,non-woody cellulosic fibers, cellulose acetate, cellulose triacetate,rayon, thermomechanical wood pulp, chemical wood pulp, debonded chemicalwood pulp, milkweed, or bacterial cellulose. The fiber length isimportant in producing the fabrics of the present invention. In someembodiments, such as flushable products, fiber length is of moreimportance. The minimum length of the fibers depends on the methodselected for forming the fibrous substrate. For example, where thefibrous substrate is formed by carding, the length of the fiber shouldusually be at least about 42 mm in order to insure uniformity. Where thefibrous substrate is formed by air-laid or wet-laid processes, the fiberlength may desirably be about 0.2 to 6 mm. Although fibers having alength of greater than 50 mm are within the scope of the presentinvention, it has been determined that when a substantial quantity offibers having a length greater than about 15 mm is placed in a flushablefabric, though the fibers will disperse and separate in water, theirlength tends to form “ropes” of fibers, which are undesirable whenflushing in home toilets. Therefore, for these products, it is desiredthat the fiber length be about 15 mm or less so that the fibers will nothave a tendency to “rope” when they are flushed through a toilet.Although fibers of various lengths are applicable in the presentinvention, desirably fibers are of a length less than about 15 mm sothat the fibers disperse easily from one another when in contact withwater. The fibers, particularly synthetic fibers, can also be crimpedThe fabrics of the present invention may be formed from a single layeror multiple layers. In the case of multiple layers, the layers aregenerally positioned in a juxtaposed or surface-to-surface relationshipand all or a portion of the layers may be bound to adjacent layers.Nonwoven webs of the present invention may also be formed from aplurality of separate nonwoven webs wherein the separate nonwoven websmay be formed from single or multiple layers. In those instances wherethe nonwoven web includes multiple layers, the entire thickness of thenonwoven web may be subjected to a binder application or each individuallayer may be separately subjected to a binder application and thencombined with other layers in a juxtaposed relationship to form thefinished nonwoven web.

In one embodiment, the fabric substrates of the present invention may beincorporated into cleansing and body fluid absorbent products, such assanitary napkins, diapers, adult incontinence products, surgicaldressings, tissues, wet wipes, and the like. These products may includean absorbent core, comprising one or more layers of an absorbent fibrousmaterial. The core may also comprise one or more layers of afluid-pervious element, such as fibrous tissue, gauze, plastic netting,etc. These are generally useful as wrapping materials to hold thecomponents of the core together. Additionally, the core may comprise afluid-impervious element or barrier means to preclude the passage offluid through the core and on the outer surfaces of the product.Desirably, the barrier means also is water-dispersible. A film of apolymer having substantially the same composition as the aforesaidwater-dispersible binder is particularly well-suited for this purpose.In accordance with the present invention, the polymer compositions areuseful for forming each of the above-mentioned product componentsincluding the layers of absorbent core, the fluid-pervious element, thewrapping materials, and the fluid-impervious element or barrier means.

The binder formulations of the present invention are particularly usefulfor binding fibers of air-laid nonwoven fabrics. These air-laidmaterials are useful for body-side liners, fluid distribution materials,fluid in-take materials, such as a surge material, absorbent wrap sheetand cover stock for various water-dispersible personal care products.Air-laid materials are particularly useful for use as a pre-moistenedwipe (wet wipe). The basis weights for air-laid non-woven fabrics mayrange from about 20 to about 200 grams per square meter (“gsm”) withstaple fibers having a denier of about 0.5-10 and a length of about 6-15millimeters. Surge, or in-take, materials need better resiliency andhigher loft so staple fibers having about 6 denier or greater are usedto make these products. A desirable final density for the surge, orin-take, materials is between about 0.025 grams per cubic centimeter(“g/cc”) to about 0.10 g/cc. Fluid distribution materials may have ahigher density, in the desired range of about 0.10 to about 0.20 g/ccusing fibers of lower denier, most desirable fibers have a denier ofless than about 1.5. Wipes generally can have a fiber density of about0.025 g/cc to about 0.2 g/cc and a basis weight of about 20 gsm to about150 gsm; specifically from about 30 to about 90 gsm, and mostspecifically from about 60 gsm to about 65 gsm.

Unlike other binder systems known in the art, the polymer formulationsof the present invention can be activated as binders without the needfor elevated temperature. While drying or water removal is useful inachieving a good distribution of the binder in a fibrous web, elevatedtemperature, per se, is not essential because the binder does notrequire crosslinking or other chemical reactions with high activationenergy to serve as a binder. Rather, the interaction with a solubleactivating compound, typically a water-compatible organic solvent, issufficient to cause the binder to become active (insoluble). Thus, adrying step can be avoided, if desired, or replaced with low-temperaturewater removal operations, such as room-temperature drying or freezedrying. Elevated temperature is generally helpful for drying, but thedrying can be done at temperatures below what is normally needed todrive crosslinking reactions. Thus, the peak temperature to which thesubstrate is exposed or to which the substrate is brought can be belowany of the following: 180° C., 160° C., 140° C., 120° C., 110° C., 105°C., 100° C., 90° C., 75° C., and 60° C., with an exemplary range forpeak web temperature of from about 50° C. to about 110° C., or fromabout 70° C. to about 140° C. Of course, higher temperatures can beused, but are not necessary in most embodiments. While polymer systems,such as commercial latex emulsions, may also comprise crosslinkerssuited for reaction at temperatures of 160° C. or higher, maintaining alower peak temperature can be beneficial in preventing development ofexcessive strength in the polymer that might otherwise hinder the waterdispersibility of the pre-moistened wipe.

Wet Wipe Wetting Composition and Wet Wipes Containing the Same

One particularly interesting embodiment of the present invention is theproduction of pre-moistened wipes, or wet wipes, from theabove-described binder compositions and fibrous materials. For wipes,the fibrous material may be in the form of a woven or nonwoven fabric;however, nonwoven fabrics are more desirable. The nonwoven fabric is,desirably, formed from relatively short fibers, such as wood pulpfibers. The minimum length of the fibers depends on the method selectedfor forming the nonwoven fabric. Where the nonwoven fabric is formed bya wet or dry method, the fiber length is desirably from about 0.1millimeters to 15 millimeters. Desirably, the nonwoven fabric of thepresent invention has a relatively low wet cohesive strength when it isnot bonded together by an adhesive or binder material. When suchnonwoven fabrics are bonded together by a binder composition, whichloses its bonding strength in tap water and in sewer water, the fabricwill break up readily by the agitation provided by flushing and movingthrough the sewer pipes.

The finished wipes may be individually packaged, desirably in a foldedcondition, in a moisture proof envelope or packaged in containersholding any desired number of sheets in a water-tight package with awetting composition applied to the wipe. The finished wipes may also bepackaged as a roll of separable sheets in a moisture-proof containerholding any desired number of sheets on the roll with a wettingcomposition applied to the wipes. The roll can be coreless and eitherhollow or solid. Coreless rolls, including rolls with a hollow center orwithout a solid center, can be produced with known coreless rollwinders, including those of SRP Industry, Inc. (San Jose, Calif.);Shimizu Manufacturing (Japan), and the devices disclosed in U.S. Pat.No. 4,667,890, issued May 26, 1987 to Gietman. Solid-wound corelessrolls can offer more product for a given volume and can be adapted for awide variety of dispensers.

Relative to the weight of the dry fabric, the wipe may desirably containfrom about 10 percent to about 400 percent of the wetting composition,more desirably from about 100 percent to about 300 percent of thewetting composition, and even more desirably from about 180 percent toabout 240 percent of the wetting composition. The wipe maintains itsdesired characteristics over the time periods involved in warehousing,transportation, retail display and storage by the consumer. Accordingly,shelf life may range from two months to two years.

Various forms of impermeable envelopes and storage means for containingwet-packaged materials, such as wipes and towelettes and the like, arewell known in the art. Any of these may be employed in packaging thepre-moistened wipes of the present invention.

Desirably, the pre-moistened wipes of the present invention are wettedwith an aqueous wetting composition, which has one or more of thefollowing properties:

(1) is compatible with the above-described binder compositions of thepresent invention;

(2) enables the pre-moistened wipe to maintain its wet strength duringconverting, storage and usage (including dispensing), as well as,dispersibility in a toilet bowl;

(3) does not cause skin irritation;

(4) reduces tackiness of the wipe, and provides unique tactileproperties, such as skin glide and a “lotion-like feel”; and

(5) acts as a vehicle to deliver “moist cleansing” and other skin healthbenefits.

The wetting composition should not act as a solvent for the binder.However, the wetting composition should contain an amount of awater-compatible organic solvent that preserves the wet strength of thewet wipe. Desirably, the wetting composition contains 5%-95% of awater-compatible organic solvent and 95%-5% water. A preferred organicsolvent is propylene glycol.

The wetting composition of the present invention may further comprise avariety of additives compatible with the water-compatible organicsolvent and the water-dispersible binder, such that the strength anddispersibility functions of the wipe are not jeopardized. Suitableadditives in the wetting composition include, but are not limited to,the following additives: skin-care additives; odor control agents;particulates; antimicrobial agents; preservatives; wetting agents andcleaning agents, such as detergents, surfactants, and some silicones;emollients; surface feel modifiers for improved tactile sensation (e.g.,lubricity) on the skin; fragrance; fragrance solubilizers; opacifiers;fluorescent whitening agents; UV absorbers; pharmaceuticals; and pHcontrol agents, such as malic acid or potassium hydroxide.

Skin-Care Additives

As used herein, the term “skin-care additives” represents additives,which provide one or more benefits to the user, such as a reduction inthe probability of having diaper rash and/or other skin damage caused byfecal enzymes. These enzymes, particularly trypsin, chymotrypsin andelastase, are proteolytic enzymes produced in the gastrointestinal tractto digest food. In infants, for example, the feces tend to be watery andcontain, among other materials, bacteria, and some amounts of undegradeddigestive enzymes. These enzymes, if they remain in contact with theskin for any appreciable period of time, have been found to cause anirritation that is uncomfortable in itself and can predispose the skinto infection by microorganisms. As a countermeasure, skin-care additivesinclude, but are not limited to, the enzyme inhibitors and sequestrantsset forth hereafter. The wetting composition may contain less than about5 weight percent of skin-care additives based on the total weight of thewetting composition. More specifically, the wetting composition maycontain from about 0.01 weight percent to about 2 weight percent ofskin-care additives. Even more specifically, the wetting composition maycontain from about 0.01 weight percent to about 0.05 weight percent ofskin-care additives.

A variety of skin-care additives may be added to the wetting compositionand the pre-moistened wipes of the present invention or includedtherein. In one embodiment of the present invention, skin-care additivesin the form of particles are added to serve as fecal enzyme inhibitors,offering potential benefits in the reduction of diaper rash and skindamage caused by fecal enzymes. U.S. Pat. No. 6,051,749, issued Apr. 18,2000 to Schulz et al., the entirety of which is herein incorporated byreference, discloses organophilic clays in a woven or nonwoven web, saidto be useful for inhibiting fecal enzymes. Such materials may be used inthe present invention, including reaction products of a long chainorganic quaternary ammonium compound with one or more of the followingclays: montmorillonite, bentonite, beidellite, hectorite, saponite, andstevensite.

Other known enzyme inhibitors and sequestrants may be used as skin-careadditives in the wetting composition of the present invention, includingthose that inhibit trypsin and other digestive or fecal enzymes, andinhibitors for urease. For example, enzyme inhibitors and anti-microbialagents may be used to prevent the formation of odors in body fluids. Forexample, urease inhibitors, which are also said to play a role in odorabsorption, are disclosed by T. Trinh in World Patent Application No.98/26808, “Absorbent Articles with Odor Control System,” published Jun.25, 1998, the entirety of which is herein incorporated by reference.Such inhibitors may be incorporated into the wetting composition and thepre-moistened wipes of the present invention and include transitionmetal ions and their soluble salts, such as silver, copper, zinc,ferric, and aluminum salts. The anion may also provide ureaseinhibition, such as borate, phytate, etc. Compounds of potential valueinclude, but are not limited to, silver chlorate, silver nitrate,mercury acetate, mercury chloride, mercury nitrate, copper metaborate,copper bromate, copper bromide, copper chloride, copper dichromate,copper nitrate, copper salicylate, copper sulfate, zinc acetate, zincborate, zinc phytate, zinc bromate, zinc bromide, zinc chlorate, zincchloride, zinc sulfate, cadmium acetate, cadmium borate, cadmiumbromide, cadmium chlorate, cadmium chloride, cadmium formate, cadmiumiodate, cadmium iodide, cadmium permanganate, cadmium nitrate, cadmiumsulfate, and gold chloride.

Other salts that have been disclosed as having urease inhibitionproperties include ferric and aluminum salts, especially the nitrates,and bismuth salts. Other urease inhibitors are disclosed by Trinh,including hydroxamic acid and its derivatives; thiourea; hydroxylamine;salts of phytic acid; extracts of plants of various species, includingvarious tannins, e.g. carob tannin, and their derivatives such aschlorogenic acid derivatives; naturally occurring acids such as ascorbicacid, citric acid, and their salts; phenyl phosphoro diamidate/diaminophosphoric acid phenyl ester; metal aryl phosphoramidate complexes,including substituted phosphorodiamidate compounds; phosphoramidateswithout substitution on the nitrogen; boric acid and/or its salts,including especially, borax, and/or organic boron acid compounds; thecompounds disclosed in European Patent Application 408,199; sodium,copper, manganese, and/or zinc dithiocarbamate; quinones; phenols;thiurams; substituted rhodanine acetic acids; alkylated benzoquinones;formarnidine disulphide; 1:3-diketones maleic anhydride; succinamide;phthalic anhydride; pehenic acid; /N,N-dihalo-2-imidazolidinones;N-halo2-oxazolidinones; thio- and/or acyl-phosphoryltnamide and/orsubstituted derivatives thereof-, thiopyridine-N-oxides, thiopyridines,and thiopyrimidines; oxidized sulfur derivatives of diarninophosphinylcompounds; cyclotriphosphazatriene derivatives; ortho-diaminophosphinylderivatives of oximes; bromo-nitro compounds; S-aryl and/or alkyldiamidophosphorothiolates; diaminophosphinyl derivatives; mono- and/orpolyphosphorodiamide; 5-substituted-benzoxathiol-2-ones;N(diaminophosphinyl)arylcarboxamides; alkoxy-1,2-benzothaizin compounds;etc.

Many other skin-care additives may be incorporated into the wettingcomposition and pre-moistened wipes of the present invention, including,but not limited to, sun blocking agents and UV absorbers, acnetreatments, pharmaceuticals, baking soda (including encapsulated formsthereof), vitamins and their derivatives such as Vitamins A or E,botanicals such as witch hazel extract and aloe vera, allantoin,emollients, disinfectants, hydroxy acids for wrinkle control oranti-aging effects, sunscreens, tanning promoters, skin lighteners,deodorants and anti-perspirants, ceramides for skin benefits and otheruses, astringents, moisturizers, nail polish removers, insectrepellants, antioxidants, antiseptics, anti-inflammatory agents and thelike, provided that the additives are compatible with an bindercomposition associated therewith, and especially the binder compositionsof the present invention (i.e., they do not cause a substantial loss ofstrength in the wet state of the pre-moistened wipes, prior to dilutionin water, while permitting dispersibility in water).

Useful materials for skin care and other benefits are listed inMcCutcheon's 1999, Vol. 2: Functional Materials, MC Publishing Company,Glen Rock, N.J. Many useful botanicals for skin care are provided byActive Organics, Lewisville, Tex.

Odor Control Additives

Suitable odor control additives for use in the wetting composition andpre-moistened wipes of the present invention include, but are notlimited to, zinc salts; talc powder; encapsulated perfumes (includingmicrocapsules, macrocapsules, and perfume encapsulated in liposomes,vessicles, or microemulsions); chelants, such as ethylenediaminetetra-acetic acid; zeolites; activated silica, activated carbon granulesor fibers; activated silica particulates; polycarboxylic acids, such ascitric acid; cyclodextrins and cyclodextrin derivatives; chitosan orchitin and derivatives thereof; oxidizing agents; antimicrobial agents,including silver-loaded zeolites (e.g., those of BF Technologies,located in Beverly, Mass., sold under the trademark HEALTHSHIELD™;triclosan; kieselguhr; and mixtures thereof. In addition to controllingodor from the body or body wastes, odor control strategies can also beemployed to mask or control any odor of the treated substrate.Desirably, the wetting composition contains less than about 5 weightpercent of odor control additives based on the total weight of thewetting composition. More desirably, the wetting composition containsfrom about 0.01 weight percent to about 2 weight percent of odor controladditives. Even more desirably, the wetting composition contains fromabout 0.03 weight percent to about 1 weight percent of odor controladditives.

In one embodiment of the present invention, the wetting compositionand/or pre-moistened wipes comprise derivatized cyclodextrins, such ashydroxypropyl beta-cyclodextrin in solution, which remain on the skinafter wiping and provide an odor-absorbing layer. In other embodiments,the odor source is removed or neutralized by application of anodor-control additive, exemplified by the action of a chelant that bindsmetal groups necessary for the function of many proteases and otherenzymes that commonly produce an odor. Chelating the metal groupinterferes with the enzyme's action and decreases the risk of malodor inthe product.

Principles for the application of chitosan or chitin derivatives tononwoven webs and cellulosic fibers are described by S. Lee et al. in“Antimicrobial and Blood Repellent Finishes for Cotton and NonwovenFabrics Based on Chitosan and Fluoropolymers,” Textile Research Journal,69(2); 104-112, Feb. 1999.

Detackifying Agents

While elevated salt concentrations may reduce the tack of the binder,other means of tack reduction are often desirable. Thus, detackifyingagents may be used in the wetting composition to reduce the tackiness,if any, of the binder. Suitable detackifiers include any substance knownin the art to reduce tack between two adjacent fibrous sheets treatedwith an adhesive-like polymer or any substance capable of reducing thetacky feel of an adhesive-like polymer on the skin. Detackifiers may beapplied as solid particles in dry form, as a suspension or as a slurryof particles. Deposition may be by spray, coating, electrostaticdeposition, impingement, filtration (i.e, a pressure differential drivesa particle-laden gas phase through the substrate, depositing particlesby a filtration mechanism), and the like, and may be applied uniformlyon one or more surfaces of the substrate or may be applied in a pattern(e.g., repeating or random patterns) over a portion of the surface orsurfaces of the substrate. The detackifier may be present throughout thethickness of the substrate, but may be concentrated at one or bothsurfaces, and may be substantially only present on one or both surfacesof the substrate.

Specific detackifiers include, but are not limited to, powders, such astalc powder, calcium carbonate, mica; starches, such as corn starch;lycopodium powder; mineral fillers, such as titanium dioxide; silicapowder; alumina; metal oxides in general; baking powder; kieselguhr; andthe like. Polymers and other additives having low surface energy mayalso be used, including a wide variety of fluorinated polymers, siliconeadditives, polyolefins and thermoplastics, waxes, debonding agents knownin the paper industry including compounds having alkyl side chains suchas those having 16 or more carbons, and the like. Compounds used asrelease agents for molds and candle making may also be considered, aswell as, dry lubricants and fluorinated release agents.

In one embodiment, the detackifier comprises polytetrafluorethylene(PTFE), such as PTFE telomer (KRYTOX® DF) compound, used in the PTFErelease agent dry lubricant MS-122DF, marketed by Miller-Stephenson(Danbury, Conn.) as a spray product. For example, PTFE particles may beapplied by spray to one side of the substrate prior to winding of thepre-moistened wipes. In one embodiment, a detackifying agent is appliedto only one surface of the substrate prior to winding into a roll.

The wetting composition desirably contains less than about 25 weightpercent of detackifying agents based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 10 weight percent of detackifying agents,more specifically about 5% or less. Even more specifically, the wettingcomposition contains from about 0.05 weight percent to about 2 weightpercent of detackifying agents.

In addition to acting as a detackifying agent, starch compounds may alsoimprove the strength properties of the pre-moistened wipes. For example,it has been found that ungelled starch particles, such as hydrophilictapioca starch, when present at a level of about 1% or higher by weightrelative to the weight of the wetting composition improves wet strength.Starch may be applied by adding the starch to a suspension of laponiteto improve the dispersion of the starch within the wetting composition.

Microparticulates

The wetting composition of the present invention may be further modifiedby the addition of solid particulates or microparticulates. Suitableparticulates include, but are not limited to, mica, silica, alumina,calcium carbonate, kaolin, talc, and zeolites. The particulates may betreated with stearic acid or other additives to enhance the attractionor bridging of the particulates to the binder system, if desired. Also,two-component microparticulate systems, commonly used as retention aidsin the papermaking industry, may also be used. Such two-componentmicroparticulate systems generally comprise a colloidal particle phase,such as silica particles, and a water-soluble cationic polymer forbridging the particles to the fibers of the web to be formed. Thepresence of particulates in the wetting composition can serve one ormore useful functions, such as (1) increasing the opacity of thepre-moistened wipes; (2) modifying the rheology or reducing thetackiness of the pre-moistened wipe; (3) improving the tactileproperties of the wipe; or (4) delivering desired agents to the skin viaa particulate carrier, such as a porous carrier or a microcapsule.Desirably, the wetting composition contains less than about 25 weightpercent of particulate based on the total weight of the wettingcomposition. More specifically, the wetting composition may contain fromabout 0.05 weight percent to about 10 weight percent ofmicroparticulate. Even more specifically, the wetting composition maycontain from about 0.1 weight percent to about 5 weight percent ofmicroparticulate.

Microcapsules and Other Delivery Vehicles

Microcapsules and other delivery vehicles may also be used in thewetting composition of the present invention to provide skin-careagents; medications; comfort promoting agents, such as eucalyptus;perfumes; skin care agents; odor control additives; vitamins; powders;and other additives to the skin of the user. Specifically, the wettingcomposition may contain up to about 25 weight percent of microcapsulesor other delivery vehicles based on the total weight of the wettingcomposition. More specifically, the wetting composition may contain fromabout 0.05 weight percent to about 10 weight percent of microcapsules orother delivery vehicles. Even more specifically, the wetting compositionmay contain from about 0.2 weight percent to about 5.0 weight percent ofmicrocapsules or other delivery vehicles.

Microcapsules and other delivery vehicles are well known in the art. Forexample, POLY-PORE® E200 (Chemdal Corp., Arlington Heights, Ill.), is adelivery agent comprising soft, hollow spheres that can contain anadditive at over 10 times the weight of the delivery vehicle. Knownadditives reported to have been used with POLY-PORE® E200 include, butare not limited to, benzoyl peroxide, salicylic aid, retinol, retinylpalmitate, octyl methoxycinnamate, tocopherol, silicone compounds (DC435), and mineral oil. Another useful delivery vehicle is a sponge-likematerial marketed as POLY-PORE® L200, which is reported to have beenused with silicone (DC 435) and mineral oil. Other known deliverysystems include cyclodextrins and their derivatives, liposomes,polymeric sponges, and spray-dried starch.

Additives present in microcapsules are isolated from the environment andthe other agents in the wetting composition until the wipe is applied tothe skin, whereupon the microcapsules break and deliver their load tothe skin or other surfaces.

Preservatives and Anti-Microbial Agents

The wetting composition of the present invention may also containpreservatives and/or anti-microbial agents. Several preservatives and/oranti-microbial agents, such as Mackstat H 66 (available from McIntyreGroup, Chicago, Ill.), have been found to give excellent results inpreventing bacteria and mold growth. Other suitable preservatives andanti-microbial agents include, but are not limited to DMDM hydantoin(e.g., Glydant Plus™, Lonza, Inc., Fair Lawn, N.J.), iodopropynylbutylcarbamate, Kathon (Rohm and Hass, Philadelphia, Pa.),methylparaben, propylparaben, 2-bromo-2-nitropropane-1,3-diol, benzoicacid, and the like. Desirably, the wetting composition contains lessthan about 2 weight percent on an active basis of preservatives and/oranti-microbial agents based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of preservatives and/oranti-microbial agents. Even more desirably, the wetting compositioncontains from about 0.01 weight percent to about 0.5 weight percent ofpreservatives and/or anti-microbial agents.

Wetting Agents and Cleaning Agents

A variety of wetting agents and/or cleaning agents may be used in thewetting composition of the present invention. Suitable wetting agentsand/or cleaning agents include, but are not limited to, detergents andnonionic, amphoteric, and anionic surfactants, especially aminoacid-based surfactants. Amino acid-based surfactant systems, such asthose derived from amino acids L-glutamic acid and other natural fattyacids, offer pH compatibility to human skin and good cleansing power,while being relatively safe and providing improved tactile andmoisturization properties compared to other anionic surfactants. Onefunction of the surfactant is to improve wetting of the dry substratewith the wetting composition. Another function of the surfactant can beto disperse bathroom soils when the pre-moistened wipe contacts a soiledarea and to enhance their absorption into the substrate. The surfactantcan further assist in make-up removal, general personal cleansing, hardsurface cleansing, odor control, and the like.

One commercial example of an amino-acid based surfactant isacylglutamate, marketed under the Amisoft name by Ajinomoto Corp.,Tokyo, Japan. Desirably, the wetting composition contains less thanabout 3 weight percent of wetting agents and/or cleaning agents based onthe total weight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 2 weightpercent of wetting agents and/or cleaning agents. Even more desirably,the wetting composition contains from about 0.1 weight percent to about0.5 weight percent of wetting agents and/or cleaning agents.

Although amino-acid based surfactants are particularly useful in thewetting compositions of the present invention, a wide variety ofsurfactants may be used in the present invention. Suitable non-ionicsurfactants include, but are not limited to, the condensation productsof ethylene oxide with a hydrophobic (oleophilic) polyoxyalkylene baseformed by the condensation of propylene oxide with propylene glycol. Thehydrophobic portion of these compounds desirably has a molecular weightsufficiently high so as to render it water-insoluble. The addition ofpolyoxyethylene moieties to this hydrophobic portion increases thewater-solubility of the molecule as a whole, and the liquid character ofthe product is retained up to the point where the polyoxyethylenecontent is about 50% of the total weight of the condensation product.Examples of compounds of this type include commercially-availablePluronic surfactants (BASF Wyandotte Corp.), especially those in whichthe polyoxypropylene ether has a molecular weight of about 1500-3000 andthe polyoxyethylene content is about 35-55% of the molecule by weight,i.e. Pluronic L-62.

Other useful nonionic surfactants include, but are not limited to, thecondensation products of C₈-C₂₂ alkyl alcohols with 2-50 moles ofethylene oxide per mole of alcohol. Examples of compounds of this typeinclude the condensation products of C₁₁-C₁₅ secondary alkyl alcoholswith 3-50 moles of ethylene oxide per mole of alcohol, which arecommercially-available as the Poly-Tergent SLF series from OlinChemicals or the TERGITOL™ series from Union Carbide, i.e. TERGITOL™25-L-7, which is formed by condensing about 7 moles of ethylene oxidewith a C₁₂-C₁₅ alkanol.

Other nonionic surfactants, which may be employed in the wettingcomposition of the present invention, include the ethylene oxide estersof C₆-C₁₂ alkyl phenols such as (nonylphenoxy)polyoxyethylene ether.Particularly useful are the esters prepared by condensing about 8-12moles of ethylene oxide with nonylphenol, i.e. the IGEPAL® CO series(GAF Corp.).

Further non-ionic surface active agents include, but are not limited to,alkyl polyglycosides (APG), derived as a condensation product ofdextrose (D-glucose) and a straight or branched chain alcohol. Theglycoside portion of the surfactant provides a hydrophile having highhydroxyl density, which enhances water solubility. Additionally, theinherent stability of the acetal linkage of the glycoside provideschemical stability in alkaline systems. Furthermore, unlike somenon-ionic surface active agents, alkyl polyglycosides have no cloudpoint, allowing one to formulate without a hydrotrope, and these arevery mild, as well as readily biodegradable non-ionic surfactants. Thisclass of surfactants is available from Horizon Chemical under the tradenames of APG-300, APG-350, APG-500, and APG-500.

Silicones are another class of wetting agents available in pure form, oras microemulsions, macroemulsions, and the like. One exemplary non-ionicsurfactant group is the silicone-glycol copolymers. These surfactantsare prepared by adding poly(lower)alkylenoxy chains to the free hydroxylgroups of dimethylpolysiloxanols and are available from the Dow ComingCorp as Dow Coming 190 and 193 surfactants (CTFA name: dimethiconecopolyol). These surfactants function, with or without any volatilesilicones used as solvents, to control foaming produced by the othersurfactants, and also impart a shine to metallic, ceramic, and glasssurfaces.

Anionic surfactants may also be used in the wetting compositions of thepresent invention. Anionic surfactants are useful due to their highdetergency include anionic detergent salts having alkyl substituents of8 to 22 carbon atoms such as the water-soluble higher fatty acid alkalimetal soaps, e.g., sodium myristate and sodium palmitate. A preferredclass of anionic surfactants encompasses the water-soluble sulfated andsulfonated anionic alkali metal and alkaline earth metal detergent saltscontaining a hydrophobic higher alkyl moiety (typically containing fromabout 8 to 22 carbon atoms) such as salts of higher alkyl mono orpolynuclear aryl sulfonates having from about 1 to 16 carbon atoms inthe alkyl group, with examples available as the Bio-Soft series, i.e.Bio-Soft D-40 (Stepan Chemical Co.).

Other useful classes of anionic surfactants include, but are not limitedto, the alkali metal salts of alkyl naphthalene sulfonic acids (methylnaphthalene sodium sulfonate, Petro AA, Petrochemical Corporation);sulfated higher fatty acid monoglycerides such as the sodium salt of thesulfated monoglyceride of cocoa oil fatty acids and the potassium saltof the sulfated monoglyceride of tallow fatty acids; alkali metal saltsof sulfated fatty alcohols containing from about 10 to 18 carbon atoms(e.g., sodium lauryl sulfate and sodium stearyl sulfate); sodiumC₁₄-C₁₆-alphaolefin sulfonates such as the Bio-Terge series (StepanChemical Co.); alkali metal salts of sulfated ethyleneoxy fatty alcohols(the sodium or ammonium sulfates of the condensation products of about 3moles of ethylene oxide with a C₁₂-C₁₅ n-alkanol, i.e., the Neodolethoxysulfates, Shell Chemical Co.); alkali metal salts of higher fattyesters of low molecular weight alkylol sulfonic acids, e.g. fatty acidesters of the sodium salt of isothionic acid, the fatty ethanolamidesulfates; the fatty acid amides of amino alkyl sulfonic acids, e.g.lauric acid amide of taurine; as well as numerous other anionic organicsurface active agents such as sodium xylene sulfonate, sodiumnaphthalene sulfonate, sodium toulene sulfonate and mixtures thereof.

A further useful class of anionic surfactants includes the8-(4-n-alkyl-2-cyclohexenyl)-octanoic acids, wherein the cyclohexenylring is substituted with an additional carboxylic acid group. Thesecompounds or their potassium salts, are commercially-available fromWestvaco Corporation as Diacid 1550 or H-240. In general, these anionicsurface active agents can be employed in the form of their alkali metalsalts, ammonium or alkaline earth metal salts.

Macroemulsions and Microemulsion of Silicone Particles

The wetting composition may further comprise an aqueous microemulsion ofsilicone particles. For example, U.S. Pat. No. 6,037,407, “Process forthe Preparation of Aqueous Emulsions of Silicone Oils and/or Gums and/orResins” issued Mar. 14, 2000, discloses organopolysiloxanes in anaqueous microemulsion. Desirably, the wetting composition contains lessthan about 5 weight percent of a microemulsion of silicone particlesbased on the total weight of the wetting composition. More desirably,the wetting composition contains from about 0.02 weight percent to about3 weight percent of a microemulsion of silicone particles. Even moredesirably, the wetting composition contains from about 0.02 weightpercent to about 0.5 weight percent of a microemulsion of siliconeparticles.

Silicone emulsions in general may be applied to the pre-moistened wipeby any known coating method. For example, the pre-moistened wipe may bemoistened with an aqueous composition comprising a water-dispersible orwater-miscible, silicone-based component that is compatible with theactivating compound in the wetting composition. Further, the wipe cancomprise a nonwoven web of fibers having a water-dispersible binder,wherein the web is moistened with a lotion comprising a silicone basedsulfosuccinate. The silicone-based sulfosuccinate provides gentle andeffective cleansing without a high level of surfactant. Additionally,the silicone-based sulfosuccinate provides a solubilization function,which prevents precipitation of oil-soluble components, such asfragrance components, vitamin extracts, plant extracts, and essentialoils.

In one embodiment of the present invention, the wetting compositioncomprises a silicone copolyol sulfosuccinate, such as disodiumdimethicone copolyol sulfosuccinate and diammonium dimethiconecopolyolsulfosuccinate. Desirably, the wetting composition comprisesless than about 2 percent by weight of the silicone-basedsulfosuccinate, and more desirably from about 0.05 percent to about 0.30percent by weight of the silicone-based sulfosuccinate.

In another example of a product comprising a silicone emulsions, DowComing 9506 powder may also be present in the wetting composition. DowComing 9506 powder is believed to comprise adimethicone/vinyldimethicone cross-polymer and is a spherical powder,which is said to be useful in controlling skin oils (see “New ChemicalPerspectives,” Soap and Cosmetics, Vol. 76, No. 3, Mar. 2000, p. 12).Thus, a water-dispersible wipe, which delivers a powder effective incontrolling skin oil, is also within the scope of the present invention.Principles for preparing silicone emulsions are disclosed in WO97/10100, published Mar. 20, 1997.

Emollients

The wetting composition of the present invention may also contain one ormore emollients. Suitable emollients include, but are not limited to,PEG 75 lanolin, methyl gluceth 20 benzoate, C₁₂-C₁₅ alkyl benzoate,ethoxylated cetyl stearyl alcohol, products marketed as Lambent waxWS-L, Lambent WD-F, Cetiol HE (Henkel Corp.), Glucam P20 (Amerchol),Polyox WSR N-10 (Union Carbide), Polyox WSR N-3000 (Union Carbide),Luviquat (BASF), Finsolv SLB 101 (Finetex Corp.), mink oil, allantoin,stearyl alcohol, Estol 1517 (Unichema), and Finsolv SLB 201 (FinetexCorp.).

An emollient can also be applied to a surface of the article prior to orafter wetting with the wetting composition. Such an emollient may beinsoluble in the wetting composition and can be immobile except whenexposed to a force. For example, a petrolatum-based emollient can beapplied to one surface in a pattern, after which the other surface iswetted to saturate the wipe. Such a product could provide a cleaningsurface and an opposing skin treatment surface.

The emollient composition in such products and other products of thepresent invention can comprise a plastic or fluid emollient such as oneor more liquid hydrocarbons (e.g., petrolatum), mineral oil and thelike, vegetable and animal fats (e.g., lanolin, phospholipids and theirderivatives) and/or a silicone materials such as one or more alkylsubstituted polysiloxane polymers, including the polysiloxane emollientsdisclosed in U.S. Pat. No. 5,891,126, issued Apr. 6, 1999 to Osborn, IIIet al. Optionally, a hydrophilic surfactant may be combined with aplastic emollient to improve wettability of the coated surface. In someembodiments of the present invention, it is contemplated that liquidhydrocarbon emollients and/or alkyl substituted polysiloxane polymersmay be blended or combined with one or more fatty acid ester emollientsderived from fatty acids or fatty alcohols.

In an embodiment of the present invention, the emollient material is inthe form of an emollient blend. Desirably, the emollient blend comprisesa combination of one or more liquid hydrocarbons (e.g., petrolatum),mineral oil and the like, vegetable and animal fats (e.g., lanolin,phospholipids and their derivatives), with a silicone material such asone or more alkyl substituted polysiloxane polymers. More desirably, theemollient blend comprises a combination of liquid hydrocarbons (e.g.,petrolatum) with dimethicone or with dimethicone and other alkylsubstituted polysiloxane polymers. In some embodiments of the presentinvention, it is contemplated that blends of liquid hydrocarbonemollients and/or alkyl substituted polysiloxane polymers may be blendedwith one or more fatty acid ester emollients derived from fatty acids orfatty alcohols. PEG-7 glyceryl cocoate, available as Standamul HE(Henkel Corp., Hoboken, N.J.), can also be considered.

Water-soluble, self-emulsifying emollient oils, which are useful in thepresent wetting compositions, include the polyoxyalkoxylated lanolinsand the polyoxyalkoxylated fatty alcohols, as disclosed in U.S. Pat. No.4,690,821, issued Sep. 1, 1987 to Smith et al. The polyoxyalkoxy chainsdesirably will comprise mixed propylenoxy and ethyleneoxy units. Thelanolin derivatives will typically comprise about 20-70 suchlower-alkoxy units while the C₁₂-C₂₀-fatty alcohols will be derivatizedwith about 8-15 lower-alkyl units. One such useful lanolin derivative isLanexol AWS (PPG-12-PEG-50, Croda, Inc., New York, N.Y.). A usefulpoly(15-20) C₂-C₃-alkoxylate is PPG-5-Ceteth-20, known as Procetyl AWS(Croda, Inc.).

According to one embodiment of the present invention, the emollientmaterial reduces undesirable tactile attributes, if any, of the wettingcomposition. For example, emollient materials, including dimethicone,can reduce the level of tackiness that may be caused by the binder orother components in the wetting composition, thus serving as adetackifier.

Desirably, the wetting composition contains less than about 25 weightpercent of emollients based on the total weight of the wettingcomposition. More specifically, the wetting composition may compriseless than about 5 weight percent emollient, and most specifically lessthan about 2% emollient. More desirably, the wetting composition maycontain from about 0.01 weight percent to about 8 weight percent ofemollients. Even more desirably, the wetting composition may containfrom about 0.2 weight percent to about 2 weight percent of emollients.

In one embodiment, the wetting composition and/or pre-moistened wipes ofthe present invention comprise an oil-in-water emulsion comprising anoil phase containing at least one emollient oil and at least oneemollient wax stabilizer dispersed in an aqueous phase comprising atleast one polyhydric alcohol emollient and at least one organicwater-soluble detergent, as disclosed in U.S. Pat. No. 4,559,157, issuedDec. 17, 1985 to Smith et al., the entirety of which is hereinincorporated by reference.

Surface Feel Modifiers

Surface feel modifiers are used to improve the tactile sensation (e.g.,lubricity) of the skin during use of the product. Suitable surface feelmodifiers include, but are not limited to, commercial debonders; andsofteners, such as the softeners used in the art of tissue makingincluding quaternary ammonium compounds with fatty acid side groups,silicones, waxes, and the like. Exemplary quaternary ammonium compoundswith utility as softeners are disclosed in U.S. Pat. No. 3,554,862,issued to Hervey et al. on Jan. 12, 1971; U.S. Pat. No. 4,144,122,issued to Emanuelsson et al., Mar. 13, 1979, U.S. Pat. No. 5,573,637,issued to Ampulski et al. Nov. 12, 1996; and U.S. Pat. No. 4,476,323,issued to Hellsten et al., Oct. 9, 1984, the entirety of all of which isherein incorporated by reference. Desirably, the wetting compositioncontains less than about 2 weight percent of surface feel modifiersbased on the total weight of the wetting composition. More desirably,the wetting composition contains from about 0.01 weight percent to about1 weight percent of surface feel modifiers. Even more desirably, thewetting composition contains from about 0.01 weight percent to about0.05 weight percent of surface feel modifiers.

Fragrances

A variety of fragrances may be used in the wetting composition of thepresent invention. Desirably, the wetting composition contains less thanabout 2 weight percent of fragrances based on the total weight of thewetting composition. More desirably, the wetting composition containsfrom about 0.01 weight percent to about 1 weight percent of fragrances.Even more desirably, the wetting composition contains from about 0.01weight percent to about 0.05 weight percent of fragrances.

Fragrance Solubilizers

Further, a variety of fragrance solubilizers may be used in the wettingcomposition of the present invention. Suitable fragrance solubilizersinclude, but are not limited to, polysorbate 20, propylene glycol,ethanol, isopropanol, diethylene glycol monoethyl ether, dipropyleneglycol, diethyl phthalate, triethyl citrate, Ameroxol OE-2 (AmercholCorp.), Brij 78 and Brij 98 (ICI Surfactants), Arlasolve 200 (ICISurfactants), Calfax 16L-35 (Pilot Chemical Co.), Capmul POE-S (AbitecCorp.), Finsolv SUBSTANTIAL (Finetex), and the like. Desirably, thewetting composition contains less than about 2 weight percent offragrance solubilizers based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of fragrance solubilizers.Even more desirably, the wetting composition contains from about 0.01weight percent to about 0.05 weight percent of fragrance solubilizers.

Opacifiers

Suitable opacifiers include, but are not limited to, titanium dioxide orother minerals or pigments, and synthetic opacifiers such asREACTOPAQUE® particles (available from Sequa Chemicals, Inc., Chester,S.C.). Desirably, the wetting composition contains less than about 2weight percent of opacifiers based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of opacifiers. Even moredesirably, the wetting composition contains from about 0.01 weightpercent to about 0.05 weight percent of opacifiers.

pH Control Agents

Suitable pH control agents for use in the wetting composition of thepresent invention include, but are not limited to, malic acid, citricacid, hydrochloric acid, acetic acid, sodium hydroxide, potassiumhydroxide, and the like. An appropriate pH range minimizes the amount ofskin irritation resulting from the wetting composition on the skin.Desirably, the pH range of the wetting composition is from about 3.5 toabout 6.5. More desirably, the pH range of the wetting composition isfrom about 4 to about 6. Desirably, the wetting composition containsless than about 2 weight percent of a pH adjuster based on the totalweight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 1 weightpercent of a pH adjuster. Even more desirably, the wetting compositioncontains from about 0.01 weight percent to about 0.05 weight percent ofa pH adjuster.

Although a variety of wetting compositions, formed from one or more ofthe above-described components, may be used with the wet wipes of thepresent invention, in one embodiment, the wetting composition containsthe following components, given in weight percent of the wettingcomposition, as shown in Table 2 below:

TABLE 2 Wetting Composition Components Wetting Composition Component:Weight Percent: Deionized Water about 86 to about 98 Organic Solventabout 5 to about 20 Preservative Up to about 2 Surtactant Up to about 2Silicone Emulsion Up to about 1 Emollient Up to about 1 Fragrance Up toabout 0.3 Fragrance solubilizer Up to about 0.5 pH adjuster Up to about0.2

In another embodiment of the present invention, the wetting compositioncomprises the following components, given in weight percent of thewetting composition, as shown in Table 3 below:

TABLE 3 Wetting Composition Components Class of Wetting Specific WettingComposition Composition Component Weight Component: Component: Name:Percent: Vehicle Deionized Water about 86 to about 98 Organic SolventPropylene glycol about 5 to about 20 Preservative Glycerin, IPBCMackstat H-66 Up to about 2 and DMDM (McIntyre Group, Hydantoin Chicago,IL) Surfactant Acyl Glutamate CS22 Up to about 2 (Ajinomoto, Tokyo,Japan) Silicone Emulsion Dimethiconol DC1785 Up to about 1 (Detackifier/and TEA (Dow Corning, Skin Feel agent) Dodecylbenezene Midland, MI)Sulfonate Emollient PEG-75 Lanolin Solulan L-575 Up to about 1(Amerchol, Middlesex, NJ) Fragrance Fragrance Dragoco Up to about 0.30/708768 (Dragoco, Roseville, MN) Fragrance Polysorbate 20 Glennsurf L20Up to about 0.5 solubilizer (Glenn Corp., St. Paul, MN) pH adjusterMalic Acid to Up to about 0.2 pH 5 (Haarman & Reimer, Teterboro, NJ)

In another embodiment of the present invention, the wetting compositioncomprises the following components, given in weight percent of thewetting composition, as shown in Table 4 below:

TABLE 4 An Exemplary Wetting Composition Class of Wetting SpecificWetting composition composition Component Component: Component: Name:Weight Percent: Vehicle Deionized Water about 93 Organic SolventPropylene glycol about 20 Preservative Glycerin, IPBC Mackstat about 1and DMDM H-66 Hydantoin Surfactant Acyl Glutamate CS22/ECS about 1 22PSilicone Dimethiconol DC1784/ about 0.5 Emulsion and TEA DC1785Dodecylbenezene Sulfonate Emollient PEG-75 Lanolin Solulan L-575 about0.25 Fragrance Fragrance Dragoco about 0.05 Fragrance 0/708768 FragrancePolysorbate 20 Glennsurf L20 about 0.25 solubilizer pH adjuster MalicAcid to about 0.07 pH 5

It should be noted that the above-described wetting compositions of thepresent invention may be used with any one of the above-described bindercompositions of the present invention. Further, the above-describedwetting compositions of the present invention may be used with any otherbinder composition, including conventional binder compositions, or withany known fibrous or absorbent substrate, whether dispersible or not.

Strength Properties

Unless otherwise specified, tensile testing is performed according tothe following protocol. Testing of dry product should be conducted underTappi conditions (50% relative humidity, 73° F.) with a proceduresimilar to ASTM-1117-80, section 7. Tensile tests are performed with aconstant crosshead speed tensile tester such as the Thwing Albert1256-100 tensile tester with an RSA-210-kg load cell. Specimens are cutto 3-inch widths and 6 inch lengths, and mounted between jaws with a4-inch gauge length. The crosshead speed is 12 inches per minute. Peakload (for tensile strength) and elongation at peak load (for stretch)are measured. For cross direction (CD) tensile tests, the sample is cutin the cross direction. For machine direction (MD) tensile tests, thesample is cut in the cross direction.

Tensile tests in the dry state are reported for webs taken prior toapplication of the wetting composition. The machine direction drytensile strength is abbreviated as “MDDT,” and the cross direction drytensile strength as “CDDT.” The results can be reported as kg/3-in orconverted to units of g/in or g/2.54 cm.

Based on the dry weight of the specimen cut to the appropriate size, anexcess amount of wetting solution (4% saline solution with no otheradditives, unless otherwise specified) is applied to reach a solutionadd-on of 250-400%. The wetted specimens are then immediately passedthrough an Atlas Lab Wringer (Atlas Electric Devices Company, Chicago,Ill. No. 10404 LW-1, no load) to uniformly distribute the solution inthe sample and gently remove the excess solution to achieve a finalsolution add-on of 200%. Several iterations or passes may be needed toreach the add-on target depending on the sample. The completed,pre-moistened samples are then bagged in plastic to prevent dry-outbefore testing.

Cross direction wet tensile tests (CDWT) or machine direction wettensile strength (MDWT) are performed as described above using thepre-moistened sample as is, after the sample has equilibrated by sittingovernight in a sealed plastic bag.

For tests related to strength loss in a pre-moistened web occurringafter exposure to a new solution, a container having dimensions of 200mm by 120 mm and deep enough to hold 1000 ml is filled with 700 ml ofthe selected soak solution. No more than 108 square inches of sample aresoaked in the 700 ml of soaking solution, depending on specimen size.The pre-moistened specimens, that have equilibrated overnight, areimmersed in the soak solution and then allowed to soak undisturbed for aspecified time period (typically 1 hour). At the completion of the soakperiod, samples are carefully retrieved from the soak solution, allowedto drain, and then tested immediately as described above (i.e., thesample is immediately mounted in the tensile tester and tested, withoutbeing passed through the wringer). In cases with highly dispersiblematerials, the samples often cannot be retrieved from the soakingsolution without falling apart. The soaked tensile values for suchsamples are recorded as zero for the corresponding solution.

For the deionized soaked cross-direction wet tensile test, S-CDWT, thesample is immersed in deionized water for 1 hour and then tested. Forthe hard-water soaked cross-direction wet tensile test, S-CDWT-M (Mindicating divalent metal ions), the sample is immersed in watercontaining 200 ppm of Ca⁺⁺/Mg⁺⁺ in a 2:1 ratio prepared from calciumchloride and magnesium chloride, soaked for one hour and then tested.For the medium hard water soaked cross-direction wet tensile test,MS-CDWT-M, the sample is immersed in water containing 50 ppm ofCa⁺⁺/Mg⁺⁺ in a 2:1 ratio, soaked for one hour and then tested. Testingdone with other time increments or soaking solutions should be soindicated to prevent confusion with the S-CDWT or S-CDWT-M tests.

The amount of wetting composition added to the nonwoven fabric, relativeto the weight of the dry nonwoven fabric in the present invention, isdesirably about 180 percent to about 240 weight percent.

Desirably, the wet wipes of the present invention possess an in-use wettensile strength (CDWT) of at least 100 g/in, and a tensile strength ofless than about 30 g/in after being soaked in water having aconcentration of Ca² ⁺ and/or Mg² ⁺ ions of about 50 ppm for about onehour (MS-CDWT-M). More desirably, the wet wipes possess an in-use wettensile strength of at least 300 g/in (CDWT), and a tensile strength ofless than about 30 g/in after being soaked in water having aconcentration of Ca² ⁺ and/or Mg²⁺ ions of about 50 ppm for about onehour (MS-CDWT-M). In a further embodiment, the wet wipes desirablypossess an in-use wet tensile strength of at least 200 g/in (CDWT), anda tensile strength of less than about 20 g/in after being soaked inwater having a concentration of Ca²⁺ and/or Mg² ⁺ ions of about 200 ppmfor about one hour (S-CDWT-M). Even more desirably, the wet wipespossess an in-use wet tensile strength of at least 300 g/in, and atensile strength of less than about 20 g/in after being soaked in waterhaving a concentration of Ca² ⁺ and/or Mg² ⁺ ions of about 200 ppm forabout one hour (S-CDWT-M).

Products with high basis weights or wet strengths than flushable wetwipes may have relatively higher wet tensile strength. For example,products such as pre-moistened towels or hard-surface cleaning wipes mayhave basis weights above 70 gsm, such as from 80 gsm to 150 gsm. Suchproducts can have CDWT values of 500 g/in or greater, with S-CDWT valuesof about 150 g/in or less, more specifically about 100 g/in or less, andmost specifically about 50 g/in or less, with similar ranges possiblefor S-CDWT-M.

Dispersibility

Prior efforts to measure dispersibility of webs, whether dry orpremoistened, have commonly relied on systems in which the web wasexposed to shear while in water, such as measuring the time for a web tobreak up while being agitated by a mechanical mixer. The constantexposure to shear offers an unrealistic and overly optimistic test forproducts designed to be flushed in a toilet, where the level of shear isweak and extremely brief. Once the product has passed through the neckof the toilet and entered a septic tank, shear rates may be negligible.Further, the product may not be fully wetted with water from the toiletbowl when it is flushed, or rather, there may not have been adequatetime for the wetting composition of the product to have been replacedwith the water of the toilet bowl when the momentary shear of flushingis applied. Thus, previous measurements of dispersibility could suggestthat a product is dispersible when, in fact, it may be poorly suited forseptic system.

For a realistic appraisal of dispersibility, it is believed that arelatively static measure is needed to better simulate the low shearthat real products will experience once they have become fully wettedwith water from the toilet. Thus, a test method for dispersibility hasbeen developed which does not rely on shear and which provides animproved means of assessing suitability of a product for a septicsystem. In this method, the tensile strength of a product is measured inits original, wetted form (the CDWT measurement described above) andafter the product has been soaked in a second solution for one hour(either the S-CDWT or S-CDWT-M test). The second solution can be eitherdeionized water for determination of the “Deionized Dispersibility”value or hard water (according to the S-CDWT-M test) for determinationof the “Hard Water Dispersibility” value. In either case, theDispersibility is defined as (1 minus the ratio of the cross-directionwet tensile strength in the second solution divided by the originalcross-direction wet tensile strength) * 100%. Thus, if a pre-moistenedwipe loses 75% of its CD wet tensile strength after soaking in hardwater for one hour, the Hard Water Dispersibility is (1-0.25)*100%=75%.The articles of the present invention can have a DeionizedDispersibility of 80% or greater, more specifically 90% or greater,specifically still 95% or greater, and can have a DeionizedDispersibility of about 100%. The articles of the present invention canhave a Hard Water Dispersibility of 70% or greater, more specifically80% or greater, specifically still about 90% or greater, and can have aDeionized Dispersibility of about 100%.

Method of Making Wet Wipes

The pre-moistened wipes of the present invention can be made in severalways. In one embodiment, the polymer composition is applied to a fibroussubstrate as part of an aqueous solution or suspension, whereinsubsequent drying is needed to remove the water and promote binding ofthe fibers. In particular, during drying, the binder migrates to thecrossover points of the fibers and becomes activated as a binder inthose regions, thus providing acceptable strength to the substrate. Forexample, the following steps can be applied:

1. Providing an absorbent substrate that is not highly bonded (e.g., anunbonded airlaid, a tissue web, a carded web, fluff pulp, etc.).

2. Applying an polymer composition to the substrate, typically in theform of a liquid, suspension, or foam.

3. Drying the substrate to promote bonding of the substrate. Thesubstrate may be dried such that the peak substrate temperature does notexceed 160° C., or 140° C., or 120° C., 110° C., or 100° C. In oneembodiment, the substrate temperature does not exceed 80° C. or 60° C.

4. Applying a wetting composition to the substrate.

5. Placing the wetted substrate in roll form or in a stack and packagingthe product.

Application of the polymer composition to the substrate can be by meansof spray; by foam application; by immersion in a bath; by curtaincoating; by coating and metering with a wire-wound rod; by passage ofthe substrate through a flooded nip; by contact with a pre-meteredwetted roll coated with the binder solution; by pressing the substrateagainst a deformable carrier containing the polymer composition, such asa sponge or felt, to effect transfer into the substrate; by printingsuch as gravure, inkjet, or flexographic printing; and any other meansknown in the art.

In the use of foams to apply a polymer binder, the mixture is frothed,typically with a foaming agent, and spread uniformly on the substrate,after which vacuum is applied to pull the froth through the substrate.Any known foam application method can be used, including that of U.S.Pat. No. 4,018,647, “Process for the Impregnation of a Wet Fiber Webwith a Heat Sensitized Foamed Latex Binder,” issued Apr. 19, 1977 toWietsma, the entirety of which is herein incorporated by reference.Wietsma discloses a method wherein a foamed latex is heat-sensitized bythe addition of a heat-sensitizer such as functional siloxane compoundsincluding siloxane oxyalkylene block copolymers and organopolysiloxanes.Specific examples of applicable heat-sensitizers and their use thereoffor the heat sensitization of latices are described in the U.S. Pat.Nos. 3,255,140; 3,255,141; 3,483,240 and 3,484,394, all of which areincorporated herein by reference. The use of a heat-sensitizer is saidto result in a product having a very soft and textile-like hand comparedto prior methods of applying foamed latex binders.

The amount of heat-sensitizer to be added is dependent on, inter alia,the type of latex used, the desired coagulation temperature, the machinespeed and the temperatures in the drying section of the machine, andwill generally be in the range of about 0.05 to about 3% by weight,calculated as dry matter on the dry weight of the latex; but also largeror smaller amounts may be used. The heat sensitizer can be added in suchan amount that the latex will coagulate far below the boiling point ofwater, for instance at a temperature in the range of 35° C. to 95° C.,or from about 35° C. to 65° C.

Without wishing to be bound by theory, it is believed that a drying stepafter application of the binder solution and before application of thewetting composition enhances bonding of a fibrous substrate by drivingthe binder to fiber crossover points as moisture is driven off, thuspromoting efficient use of the binder. However, in an alternativemethod, the drying step listed above is skipped, and the polymercomposition is applied to the substrate followed by application of thewetting composition without significant intermediate drying. In oneversion of this method, the polymer composition selectively adheres tothe fibers, permitting excess water to be removed in an optionalpressing step without a significant loss of the binder from thesubstrate. In another version, no significant water removal occurs priorto application of the wetting composition. In yet another alternativemethod, the polymer composition and the wetting composition are appliedsimultaneously, optionally with subsequent addition of water-compatibleorganic solvent.

The present invention is further illustrated by the following examples,which are not to be construed in any way as imposing limitations uponthe scope thereof. On the contrary, it is to be clearly understood thatresort may be had to various other embodiments, modifications, andequivalents thereof which, after reading the description herein, maysuggest themselves to those skilled in the art without departing fromthe spirit of the present invention and/or the scope of the appendedclaims.

As used herein, the “thickness” of a web is measured with a 3-in acrylicplastic disk connected to the spindle of a Mitutoyo Digimatic Indicator(Mitutoyo Corporation, 31-19, Shiba 5-chome, Minato-ku, Tokyo 108,Japan) and which delivers a net load of 0.05 psi to the sample beingmeasured. The Mitutoyo Digimatic Indicator is zeroed when the disk restson a flat surface. When a sample having a size at least as great as theacrylic disk is placed under the disk, a thickness reading can beobtained from the digital readout of the indicator. Water-dispersiblesubstrates of the present invention can have any suitable thickness,such as from about 0.1 mm to 5 mm. For wet wipes, thicknesses can be inthe range of 0.2 mm to about 1 mm, more specifically from about 0.3 mmto about 0.7 mm. Thickness can be controlled, for example, by theapplication of compaction rolls during or after web formation, bypressing after binder or wetting composition has been applied, or bycontrolling the tension of winding when forming a roll good.

The use of the platen method to measure thickness gives an averagethickness at the macroscopic level. Local thickness may vary, especiallyif the product has been embossed or has otherwise been given athree-dimensional texture.

EXAMPLE 1

The nine binder solutions shown below were applied via a #20 wire-woundrod to 10 identical water-dispersible, wet-laid webs composed of BFErayon fibers (1.5 d×25 mm). The fabric samples were dried in aforced-air oven at 500° C. The add-on level was between 150 and 200 wt %based on the total weight of the fabric. The nonwoven sheets were cut toprovide 1 inch×3 inch strips from each sheet. The strips were tested forCDWT and SCDWT according to the following procedure.

CDWT:

The 1″×3″ strips from the 10 nonwoven sheets were soaked in the wipesolutions #1-#10 for 12 hours. The samples were removed from thesolutions and tested for tensile strength in the cross direction usingthe procedure outlined above.

SCDWT:

The 1″×3″ strips from the 10 nonwoven sheets were soaked in a solutionof 200 ppm Ca²⁺ for 1 hour. The samples were removed from the solutionsand tested for tensile strength in the cross direction using theprocedure outlined above.

The results are shown in Table 4 below.

TABLE 4 Technical Performance of Kao's Binder Binder Binder SolutionType Wipe solution CDWT SCDWT 1 Sodium 20% propylene 1190 gm/in 1.4gm/in  carboxymethyl glycol, 2.5% cellulose CaCl₂.2H₂O (“CMC”) 2 SodiumCMC 20% propylene 1138 gm/in 8.5 gm/in  glycol, 6% ZnSO₄.7H₂O 3 Sodium20% propylene  480 gm/in 77 gm/in polyacrylate glycol, 2.5% (Mwt =400,000) CaCl₂.2H₂O 4 Sodium 20% propylene  359 gm/in 260 gm/in polyacrylate glycol, 6% (Mwt = 400,000) ZnSO₄.7H₂O 5 Blend 83% 20%propylene 1207 gm/in 13 gm/in Sodium glycol, 6% polyacrylate ZnSO₄.7H₂O(Mwt = 400,000), 17% Rhoplex NW-1715K (T_(g) = ˜ −15 C) 6 Blend 83% 20%propylene 1288 gm/in 34 gm/in Sodium glycol, 2.5% polyacrylateCaCl₂.2H₂O (Mwt = 400,000), 17% Rovene 4457 (T_(g) = ˜ −7 C) 7 Blend 83%20% propylene  648 gm/in 42 gm/in Sodium glycol, 6% polyacrylateZnSO₄.7H₂O (Mwt = 400,000), 17% Rovene 4457 (Tg = ˜ −7 C) 8 Blend 83%20% propylene 1387 gm/in 50 gm/in Sodium glycol, 2.5% polyacrylateCaCl₂.2H₂O (Mwt = 400,000), 17% Rovene 4817 (T_(g) = ˜ −4 C) 9 Blend 83%20% propylene  778 gm/in 44 gm/in Sodium glycol, 6% polyacrylateZnSO₄.7H₂O (Mwt = 400,000), 17% Rovene 4817 (T_(g) = ˜ −4 C)

It should be understood, of course, that the foregoing relates only tocertain disclosed embodiments of the present invention and that numerousmodifications or alterations may be made therein without departing fromthe spirit and scope of the invention as set forth in the appendedclaims.

What is claimed is:
 1. A composition comprising: approximately 50% to95% by weight sodium polyacrylate; and approximately 5% to 50% by weightof a styrene emulsion.
 2. The composition of claim 1, wherein thestyrene emulsion is selected from styrene acrylic or styrene-butadieneemulsion.
 3. The composition of claim 1, wherein the compositioncomprises approximately 83% by weight sodium polyacrylate andapproximately 17% by weight styrene emulsion.
 4. The composition ofclaim 1, wherein said composition is sprayable.